Priority Mac:- A Priority-Enhanced MAC Protocol for Critical Traffic in Industrial Wireless Sensor and Actuators Networks. SUMMARY:- The paper proposes Priority MAC, IWSAN i.e Industrial Wireless Sensor Networks design for critical traffic. The Priority MAC also handles different traffic categories with different latency requirements, it achieves an improvement in the delivery latency compared with current industrial standards. There are 4 contributions in the paper. 1] Wireless HART and ISA 100.11.a, as a baseline and employes a novel MAC scheme to enhance access for critical and aperiodic traffic. 2] The Priority MAC reduction in latency of 94% for highest priority traffic. 93% for secondary priority traffic. Third priority is achieved at the expense of only 0.17% and 0.19% deferring ratio from the lowest priority packets. 3] Priority MAC is implemented using TINY OS 4] It is evaluated on a testbed of TelosB motes: Essays